#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>

int main() {
    int n;
    scanf("%d", &n);
    int num;
    for (int j = 1; j <= n; j++) {
        for (int i = j; i > 0; i--) {
            num += i;
        }
    }
    printf("%d", num);

    return 0;
}